I was just dealing with this this morning! Here's what I think my problem was, check your settings. First, I had a mic input selected on the "sources" block which I think was doubling my input as the "audio mixer" block already had my mic source. Also, when I then selected the mic input I am using in the "audio mixer block" I turned monitoring off and only selected Track 1. Also ensure that if you have studio monitors, that you aren't getting output from your speakers that are feeding back into the mic. Those tips should help you to get rid of the cave echo sound I was getting.
